1. Field of the Invention
The present invention relates to a multi-layer color light-sensitive material and, more particularly, to an improved multi-color light-sensitive material wherein at least one silver halide light-sensitive layer containing a dye image-forming coupler comprises a plurality of silver halide unit emulsion layers.
2. Description of the Prior Art
As is well known, multi-layer color light-sensitive materials comprise a support such as cellulose ester, polyester or paper having coated thereon light-sensitive layers such as a red-sensitive silver halide emulsion layer containing a diffusion-resistant cyan image-forming coupler, a green-sensitive silver halide emulsion layer containing a diffusion-resistant magenta image-forming coupler and a blue-sensitive silver halide emulsion layer containing a diffusion-resistant yellow image-forming coupler, the coating order of these light-sensitive layers varying depending upon the end use thereof.
British Pat. No. 818,687 suggests to raise the sensitivity of a multi-layer color light-sensitive material by using at least one emulsion layer which comprises two unit emulsion layers, one a less sensitive unit emulsion layer and one a more sensitive unit emulsion layer, the former being nearer to a support and the latter being provided thereon. In this case, the two unit emulsion layers contain couplers in the same concentration and are sensitized to the same spectral region. However, this type of light-sensitive material involves the disadvantage that the graininess of color images is coarse, though sensitivity is somewhat imcreased.
In order to remove this disadvantage, British Pat. No. 923,045 suggests graininess can be improved by the more sensitive unit emulsion layer (coarse graininess layer) providing a much lower density than that of the less sensitive unit emulsion layer. With this improvement, however, sensitivity is not sufficiently raised and the degree of fineness of grains is not sufficient.
U.S. Pat. No. 3,516,831 teaches that to improve the sharpness of color images a 4-equivalent coupler is incorporated in the more sensitive unit emulsion layer and a 2-equivalent coupler is incorporated in the less sensitive unit emulsion layer, the two unit emulsion layers constituting one emulsion layer and being sensitive to at least one spectral region which is the same. However, the defect is encountered that color fog is caused in unexposed areas due to the 2-equivalent coupler.
Furthermore, U.S. Pat. No. 3,726,681 teaches raising the sensitivity and making the grains finer by incorporating a rapid coupling coupler in the more sensitive unit emulsion layer and a slow coupling coupler in the less sensitive unit emulsion layer, the two unit emulsion layer constituting one emulsion layer and being sensitive to at least one spectral region which is the same. However, this involves the disadvantage that color fog is caused by the rapid coupling coupler in the more sensitive unit emulsion layer.